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This study aims to develop Ni-P coatings with high P content (≥11 wt.%) reinforced with WC nanoparticles on F22 steel substrates. The introduction of conductive WC in the plating solution dramatically increases reactivity of the plating solution, and consequently a tuning of deposition parameters, in terms of temperature and WC concentration, is required to obtain nanocomposite coatings with improved mechanical properties. The coatings' porosity and incorporation and dispersion of the reinforcing phase as a function of temperature and WC concentration were analyzed by quantitative image analysis from Scanning Electron Microscopy (SEM) micrographs. Increasing the temperature and concentration of nanoparticles leads to a faster plating rate and a dramatic increase in both porosity and agglomeration of the reinforcing phase, with detrimental effects on the coatings' microhardness. The best compromise between coating parameters was obtained by deposition at 70 °C and 6.5 g/L of WC, with a plating rate ≈ 12 μm/h, porosity lower than 1.5%, and a good combination between particle incorporation and agglomeration. In these conditions, a hardness increase by 34% is achieved in comparison to standard Ni-P. Coatings were then heat treated in air at 200 °C for 2 h, to induce growing stress relaxation, or 400 °C for 1 h, to study effects of crystallization and precipitation. X-Ray Diffraction (XRD) analysis demonstrated that WC introduction does not alter the microstructure of Ni-P coatings, but delays grain growth coarsening of precipitates. Hardness improvement by 6.5% and 45% is registered after treatment at 200 °C and 400 °C, respectively. An increase in elastic modulus, measured by instrumented indentation, was found in WC-reinforced coatings compared with Ni-P. Potentiodynamic polarization tests revealed that both introduction of WC nanoparticles and heat treatment also enhance corrosion resistance. [ABSTRACT FROM AUTHOR]

Unalloyed copper objects were produced in the Chalcolithic Southern Levant in a two‐step process. Copper ore was smelted in pit furnaces, and the mechanically extracted copper prills melt in crucibles and cast into objects. However, the air supply remained unknown, and practical considerations shed doubt on the validity of some of the reconstructed practices. To refine the reconstruction, the metallurgical material from Abu Matar was reassessed. Most importantly, several previously unreported fragments suggest the use of bellows and covering the furnace with large pottery fragments. Our results provide probably the earliest evidence for the use of bellows. [ABSTRACT FROM AUTHOR]

Shape memory effect (SME) and the relation with corrosion behavior of Cu-Zn-Al Smart Memory Alloys (SMAs) were investigated using different techniques: Scanning Electron Microscopy equipped with an Energy Dispersive System, X-Ray Diffraction analysis, Electrochemical Test in NaCl solutions with different concentrations (0.035%, 0.35% and 3.5%), which simulate coastal conditions, mechanical characterization through tensile test and guided bend test. SMAs are an important class of smart materials able to recover after deformation a pre-imposed shape through a temperature modification. These alloys show great potential, finding several applications in medicine and in different types of industry sectors (aerospace, architecture, automotive etc.). Cu-based SMAs, including Cu-Zn-Al alloys, have lower production costs with respect to Ni-Ti alloys as well as good possibility in seismic and architectural applications. A Cu-Zn-Al alloy with a theoretical composition of 25 wt.% Zn and 4 wt.% Al was produced by casting method. The aim of this study is to characterize the microstructure, the mechanical properties and the corrosion behavior through different kind of standard corrosion tests of this alloy and to evaluate the effect of corrosion damage on the shape memory recovery capability through a combination of corrosion and thermo-mechanical cyclic test and SEM observations. [ABSTRACT FROM AUTHOR]